Typically, materials extruded from 3D printers form structural components or sacrificial elements. The structural materials form some part of the finished printed product and the sacrificial elements typically form support structures for the other printed components and then are discarded. Some printers simultaneously print multiple materials, with different Young's modulus properties, conductive inks for wire, conductive pads, antenna, etc. and picked and placed chips.
In addition, circuit designs often contain a mix of narrow regions, approximately the bead width of the extruded material, as well as thicker regions which require multiple passes along a tool path to fill. Most tool path patterns for extruded, additive manufacturing consist of some mix of contour-parallel offsets of the part boundary, and parallel, zig-zag lines. Zig-zag lines typically consist of contour parallel lines for surface quality and zig-zag for simplicity.
However, to avoid excessive buildup of material, tool path patterns have a minimum spacing constraint that limits how close tool path lines can come to each other. Depending upon the geometry of the object to be printed, using zig-zag or contour parallel patterns and guaranteeing minimum spacing may mean that object are printed with large gaps and narrow regions, 1 bead thick, cannot be printed at all.
While patents exist the mention pattern generation for narrow features in a model, such as in U.S. Pat. No. 6,823,320, and Vona, et al. “Voronoi Toolpaths for PCB Mechanical Etch: Simple and Intuitive Algorithms with the 3D GPU,” Robotics and Automation, 2005, ICRA 2005. Proceedings of the 2005 IEEE International Conference on, IEEE 2005), they do not address the problem of guaranteeing a good conductive bond to function as a conductive wire, antenna, etc. These approaches focus on generating a space filling curve.
These approaches use the Medial Axis Transform to divide a region, into narrow and thick regions. The narrow regions are filled with a tool path pattern that follows their medial axis. The thick regions are filled using some combination of contour parallel and zig-zag patterns. However, while superficially the entire polygon is filled with material, the conductive bond between the pattern through the narrow region, sometimes referred to as the wire region, and the thick region may be poor or not even function. Most commercial tool path solutions do not even do this, though they just leave narrow regions unprinted.